Li-ion batteries in portable electronic devices typically undergo different charging, discharging and storage routines based on their use. Batteries that employ Li-ion cell chemistry may produce gas when they are improperly charged, shorted or exposed to high temperatures. This gas can be combustible and may compromise the reliability and safety of such batteries. A current interrupt device (CID) is typically employed to provide protection against any excessive internal pressure increase in a battery by interrupting the current path from the battery when pressure inside the battery is greater than a predetermined value. The CID typically includes first and second conductive plates in electrical communication with each other. The first and second conductive plates are, in turn, in electrical communication with an electrode and a terminal of the battery, respectively. The second conductive plate separates from (e.g., deforms away or is detached from) the first conductive plate of the CID when pressure inside the battery is greater than a predetermined value, whereby a current flow between the electrode and the terminal is interrupted.
Generally, however, CIDs that have been incorporated within batteries significantly limit the capacity of batteries by a large amount of space within the batteries. Further, generally, a positive thermal coefficient (PTC) layer which is in electrical communication with a negative terminal of the battery is placed over the CID, and also occupies space within the batteries. PTC layers typically are employed in batteries to provide protection against short circuits external to batteries, i.e., by interrupting the current path when an overcurrent or an overvoltage is supplied.
Therefore, there is a need for a new battery design to accommodate a CID for safety of the battery, but yet minimizing the space occupied by the CID within the battery.